I don't dare dream of her being the time traveller because that's too exciting. I'll keep my expectations low because if she's isn't the focal point, it'll be sooo disappointing.

But there is a HUUUGGEEE possibility that this can happen now that she's cast.

She can't be, not like in the comics anyway. This Kitty was born in what, the late 80s, early 90s? She's not going to have so much as a "twinkle in her dad's eye" to travel back to, let alone a physical body.